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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
    
        console.log(typeof "hello");//string
        console.log(typeof "true");//string
        console.log(typeof "123123");//string
        console.log(typeof "{}");//string
        console.log(typeof "function(){}");//string
        console.log(typeof "undefined");//string
    
        console.log(typeof 123);//number
        console.log(typeof -123);//number
        console.log(typeof -123.345);//number
        console.log(typeof NaN);//number
    
        console.log(typeof true);//boolean
        console.log(typeof false);//boolean
        
        console.log(typeof undefined);//undefined
        
        console.log(typeof function(){});//function
        
        console.log(typeof {});//object
        console.log(typeof []);//object
        
        console.log(typeof null);//null
    
    
        // 注意点：（面试题）
        console.log(typeof typeof true);//string
        // typeof的检测结果以什么类型存在？字符
        // 多个typeof检测结果必然是string
    
    </script>
</body>
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